Acquisitions Purchase Accounting Fair Value Adjustments (Details) - USD ($) $ / shares in Units, $ in Thousands	May. 31, 2015	Apr. 01, 2015	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Purchase Accounting Fair Value Adjustments [Line Items]
Goodwill			$ 285,512	$ 180,128	$ 120,164
Monarch Community Bancorp [Member]
Purchase Accounting Fair Value Adjustments [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares		860,575
Business Combination, Consideration Transferred, Value of Stock Issued		$ 26,988
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock		203
Business Combination, Consideration Transferred		27,191
Net Assets Acquired, Acquiree Shareholders Equity		15,270
Purchase Accounting Fair Value Adjustment, Loans		(7,150)
Purchase Accounting Fair Value Adjustment, Allowance for Loan Losses		2,128
Business Combination, Fair Value Adjustment, Deferred Tax Asset NOL		7,900
Purchase Accounting Fair Value Adjustment, Premises and Equipment		(370)
Purchase Accounting Fair Value Adjustment, Core Deposit Intangible Asset		1,930
Purchase Accounting Fair Value Adjustment, Mortgage Servicing Rights Asset		315
Purchase Accounting Fair Value Adjustment, Deferred Tax Asset, Net		1,748
Purchase Accounting Fair Value Adjustment, Other Assets and Liabilities, Net		37
Net Assets Acquired After Purchase Accounting Fair Value Adjustments		21,808
Goodwill		$ 5,383
Business Acquisition, Price Per Share of Common Stock Issued		$ 31.36
Lake Michigan Financial Corp [Member]
Purchase Accounting Fair Value Adjustments [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	4,322,101
Business Combination, Consideration Transferred, Value of Stock Issued	$ 130,916
Business Combination, Consideration Transferred, Value of Stock Options	2,000
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock	54,478
Business Combination, Consideration Transferred	187,394
Net Assets Acquired, Acquiree Shareholders Equity	89,280
Purchase Accounting Fair Value Adjustment, Loans	(22,600)
Purchase Accounting Fair Value Adjustment, Allowance for Loan Losses	15,888
Purchase Accounting Fair Value Adjustment, Premises and Equipment	(2,333)
Purchase Accounting Fair Value Adjustment, Core Deposit Intangible Asset	7,303
Purchase Accounting Fair Value Adjustment, Deferred Tax Asset, Net	2,269
Purchase Accounting Fair Value Adjustment, Deposits and Other Borrowings	(3,048)
Purchase Accounting Fair Value Adjustment, Other Assets and Liabilities, Net	(633)
Net Assets Acquired After Purchase Accounting Fair Value Adjustments	87,392
Goodwill	$ 100,002
Business Acquisition, Price Per Share of Common Stock Issued	$ 30.29